asp.net mvc#sqkbulkcopy一个或多个必需参数未给定值

我遇到此错误

没有为一个或多个必需参数提供值

错误的原因可能是什么。这是密码

  string excelConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + postdir + newFileNameOnServer + "; Extended Properties=Excel 8.0";


         using (OleDbConnection connection =new OleDbConnection(excelConnectionString))
         {
             OleDbCommand command = new OleDbCommand("Select Month,Year,CountryofExport,CountryofOrigin,Hs_code,quantity,Unit,CustomValue,Type FROM [qryTradeFlowforWeb$]", connection);
             connection.Open();

         // Create DbDataReader to Data Worksheet
           using (DbDataReader dr = command.ExecuteReader())   // the error coming here
           {
               string sqlConnectionString = ConfigurationManager.ConnectionStrings["KMFConnectionString"].ToString();
               SqlConnection conn = new SqlConnection(sqlConnectionString);
              using (SqlBulkCopy bulkCopy =  new SqlBulkCopy(sqlConnectionString))
              {
                bulkCopy.DestinationTableName = "ExcelData";
                bulkCopy.WriteToServer(dr);
              }
           }
      }

比较目的表clolum列表与源表列列表是否相同。如果没有，请使用映射源和目标列的详细信息

bulkCopy.ColumnMappings.Add("SourceCol", "DestinationCol1");
bulkCopy.ColumnMappings.Add("SourceCo2", "DestinationCol2");
bulkCopy.ColumnMappings.Add("SourceCo3", "DestinationCol3");

比较目的表clolum列表与源表列列表是否相同。如果没有，请使用映射源和目标列的详细信息

bulkCopy.ColumnMappings.Add("SourceCol", "DestinationCol1");
bulkCopy.ColumnMappings.Add("SourceCo2", "DestinationCol2");
bulkCopy.ColumnMappings.Add("SourceCo3", "DestinationCol3");